When operating brushless electric motors, it is required to generate a desired motor torque to ensure error-free electronic commutation. Error-free electronic commutation presupposes a current supply to the various motor coils in the right direction and at the right moment.
For this purpose, it is necessary as accurately as possible to determine the position and direction of rotation of the rotor of the electric motor. The position of the rotor can be determined by especially using Hall sensors. For example, one can arrange Hall sensors in a manner staggered with respect to each other in the direction of rotation of the rotor. The position of the rotor can then definitely be determined on the basis of a Hall sensor signal pattern supplied by the Hall sensors. In other words, one rotation of the rotor corresponds to a certain sequence of Hall sensor signals.
Even if only one erroneous sensor signal is present, that will result in an erroneous rotor position determination. In light of traditional commutation, this causes the defective triggering of the electric motor so that the rotor cannot move at all and so that the electric motor cannot generate a torque.
To prevent any kind of trouble, it is therefore necessary—if defective sensor signals occur—to ensure the electronic commutation of the electric motor so that the electric motor can continue to be operated.